Trehalose accumulation induced during the oxidative stress response is independent of TPS1 mRNA levels in Candida albicans

Abstract

Growing cells of the Candida albicans trehalose- deficient mutant tps1/tps1 were extremely sensitive to severe oxidative stress exposure (H₂O₂). However, their viability was not affected after saline stress or heatshock treatments, being roughly equivalent to that of the parental strain. In wild-type cells, these adverse conditions induced the intracellular accumulation of trehalose together with activation of trehalose-6P synthase, whereas the endogenous trehalose content and the corresponding biosynthetic activity were barely detectable in the tps1/tps1 mutant. The addition of cycloheximide did not prevent the marked induction of trehalose-6P synthase activity. Furthermore, the presence of H₂O₂ decreased the level of TPS1 mRNA expression. Hence, the conspicuous trehalose accumulation in response to oxidative stress is not induced by increased transcription of TPS1. Our results are consistent with a specific requirement of trehalose in order to withstand a severe oxidative stress in C. albicans, and suggest that trehalose accumulation observed under these conditions is a complex process that most probably involves post-translational modifications of the trehalose synthase complex.